Zvezda M503

The M503 was designed in the 1970s by Maschinenfabrik Zvezda in Leningrad ( Leningradski maschinostroitelny zavod « Zvezda » imeni K.Е.Woroschilowa ) as a motor for fast patrol boats Osa class. It is a water -cooled engine with 42 cylinders sequence star ( seven cylinder banks, each with six cylinders per bank).

Description of the engine

The engine has seven overhead camshafts (one per cylinder bank - OHC ), which are driven by also seven vertical shafts. Each camshaft carries two cams per cylinder. Each cam actuates a respective inlet and an exhaust valve on separate roller rocker. The one-piece, very solid, roller-bearing crankshaft pulley is bent six times - for each of the six stars once. The offset angle of the individual offsets be as in -line six cylinder 0 °, 120 °, 240 °, 240 °, 120 °, 0 °. So even firing intervals are achieved (all 17.14 ... ° of crankshaft rotation ignition ).

The cylinder blocks are mounted to the crankcase with tie rods which are screwed into the sections of the crankcase. The crankcase is made of seven steel sections which are interconnected with fitting bolts. The crankshaft runs in seven crankcase roller bearings, of which the thrust bearing ( bearing 7 ) locks the crankshaft in the axial direction. The engine has leading and guided blocks. Leading the blocks 1, 3 and 7 At low speeds, they are service providers.

From 1200 rpm speed the run blocks with switched. On the OSA speedboats three of these were driven diesel as the main drive. This is a fixed-pitch propeller drive, the drive levels are consequently achieved by changing the speeds. All supply pumps for diesel fuel, lubricating oil and cooling water are designed as attached and pumps so that no external power supply units. For immediate use, the cooling water and the lubricating oil were preheated to corresponding temperatures. The machine by hand were to rise preparation and with low pressure air (max. 12 bar) getörnt. Main purpose was to avoid hydraulic shocks in the hanging down blocks 1 and 7 Immediately thereafter, the engines were, after backing pumps on Vorpumpaggregate for diesel fuel and lubricating oil, started with compressed air.

The lubrication diagram of the motor

The lubricating oil is sucked by the vacuum pump and is pumped through a generator housed in the part of the motor control filter to the main oil duct of the engine for lubrication of the vorbeheizbaren circulation vessel. The oil is removed via a lying in the crotch of the cylinder block 1 and 7 collector to the oil sump of the housing of Umsteuerkupplung from the engine. In this, the oil is pumped from the bottom two cylinder blocks and the housing of the transmission by specific Ölabsaugpumpen. The oil is extracted and pumped back through a separately installed switchable dual oil filter and cooler in the circulation tank from the oil sump.

The oil cooler was, as well as the fresh water cooler, cooled by sea water. To regulate the lubricating oil cooler feature a thermostat control unit was right on the radiator available. Only one of the double oil filter was in operation mode. Operation to the other filter could be changed, if necessary in the current. After switching off the engine, the rest of the returning oil was pumped into the transmission sump and checked the oil level in the transmission sump with a dipstick. The same control was performed immediately before starting the engine - the transmission sump had to be almost empty.

The following speed steps were available:

  • 3 × 800 rpm
  • 3 × 1000 rpm
  • 3 × 1200 rpm
  • 3 × 1500 rpm
  • 3 × 1700/min
  • 3 × 1900 rpm
  • 3 × 2000 rpm
  • 3 × 2200 rpm AK- drive

Furthermore, the engine has a turbo compound charging with three hydrodynamic couplings. Since in the lower rotational speed and power range, the exhaust gas energy is not enough to bring the large turbocharger to the necessary speed, the supercharger is driven by means of a hydrodynamic coupling from the crankshaft - similar to a compressor. At high engine speeds, and associated high power the turbine of the exhaust gas turbocharger has excess energy is delivered via the hydrodynamic coupling directly to the crankshaft.


  • Type: vierventiliger, water-cooled 42- cylinder four-stroke turbo- compound diesel engine (168 valves, OHC - controlled)
  • Stroke: 170 mm
  • Bore: 160 mm
  • Capacity: 143.6 liters
  • Power: 2940 kW or 4000 HP at 2200 rpm
  • Length: 3700 mm
  • Diameter: 1560 mm
  • Mass: 5450 kg (dry)
  • Reversal: direct, through Umsteuerkupplung
  • Reversal ahead: Reibungssynchronisator, from 1200 rpm rigid coupling
  • Reversing back: planetary gearbox with brake band
  • Reversal with: Reprogramming via air dome, two dome air bottles 150 bar air pressure dome
  • Reversal on: circuit directly to the motor, remote control with Serna or Orion plant
  • Cooling system: indirect
  • Cooling water directly: condensate with shell dromus - B addition
  • Fuel: DK1
  • Compaction: 13
  • Charge air pressure: max. 2.1 bar (without intercooler, available only from M504 A)
  • The engine coolant: about 160 kg
  • Oil in the engine: about 70 kg
  • Numbering of cylinders in the block: 1-6 starting on the turbocharger side
  • Numbering of the cylinder blocks: 1-7 starting on the turbocharger side
  • Voreinspritzwinkel: 23 ° to 28 ° before TDC
  • Specific fuel consumption: 231 g / kWh ( 170 g / hp-hr )
  • Operating time: 500 hours, after which the machine change was made on the OSA - boats

Other rich cylinder engines

Its bigger brother, the Zvezda M520, even has 56 cylinders.

An engine with 42 cylinders were otherwise only from Curtiss- Wright. The Aeronautical Division of the Wright designed airplane engine Wright R -2160 Tornado with two turbochargers was also a water-cooled radial engine number seven cylinder banks of six cylinders. It was developed in the 1940s, but no longer produced in series. Despite the 42 cylinder divided, relatively small total engine displacement of 35.4 liters was his performance impressive 2500 hp at 4600 rpm in high altitudes. However, its crankshaft was not integral but divided into three sections, the three crank shafts were each ( each having two crank pins ) are coupled to one another via a total of six intermediate shafts.